The present invention relates to a dewatering device for paper machines, comprising a supporting member meant to be attached substantially transversally below the horizontal paper machine wire and a water removal blade to be fitted on top of it by means of a sliding joint.
Previously known is a stationary paper machine dewatering device for removing liquid from the horizontal wire. One especially common has been a water removal device the front part of which extends transversally in regard to the running direction of the machine to support the wire, and the supporting part of which forms an angle with the wire so that when the wire moves a vacuum is created under the wire, sucking water from the stock track.
Owing to the wear caused by the wire, the water removal device must either be made from a very expensive material, e.g., a ceramic one, or it must be easy to replace. Canadian Patent 666,214 can be mentioned as one example of the latter alternative. In it the water removal blade has been dovetailed to its support so that it can be drawn out of the machine, sliding along the support.
There is a problem connected with such a replaceable water removal blade. If the joint between the support and the water removal blade is slack in order that the blade be easy to replace, the joint is not stable but the angle between the blade and the wire can change during the operation and is susceptible to vibration. If the joint is very tight so that the blade will not move during the operation, the blade is difficult to replace. A considerable disadvantage lies in that the temperatures of the stocks for different qualities of paper are different. Since the heat expansion of HD-polyethylene and that of steel are different, a clearance suitable when the operation takes place at the temperature of one type of stock may become slack when the operation takes place with a stock at a different temperature.
The object of the invention is to eliminate the above disadvantage and provide a water removal device attachment mechanism by means of which the water removal blade is easy to replace but stays firmly in place in the operating position.